The present invention relates to the installation of offshore structures such as drilling platforms, and in particular, to the grouting-in-place of support piles which anchor an offshore structure to the seabed.
Offshore structures of the type to be utilized in the drilling of subsea oil or gas wells may comprise a jacket structure which is erected upon the seabed and a platform which is supported upon the jacket above the water surface. Generally, the jacket is fabricated at a land-based facility, then towed in a floating condition to an offshore work site, and thereafter erected within the water and lowered onto the seabed. The jacket may comprise a plurality of legs onto which a platform is mounted above the water surface. At the lower end of each leg a pile sleeve cluster may be provided which comprises a series of pile sleeves through which steel piles can be lowered and driven into the seabed by suitable pile driving equipment actuated from the surface. Pile sleeve clusters of this type are disclosed for example in U.S. Pat. No. 3,987,636 issued to Hruska et al on Oct. 26, 1976 and assigned to the assignee of this invention. The disclosure of that patent is hereby incorporated by reference as if set forth at length herein.
Once the piles have been installed, they are secured in place by introducing grouting into an annulus formed between each pile and its associated sleeve.
Among previously proposed techniques for the grouting of piles is the provision of grout supply and discharge conduits for each pile sleeve. Each supply conduit extends between the platform and a lower end of the associated pile sleeve annulus, and each discharge conduit extends between an upper end of the pile sleeve annulus and the platform. Grout is delivered through the supply conduit to fill the annulus and is then discharged to the surface to indicate that the grouting process has been completed. It will be appreciated that the need to provide two conduits per pile sleeve, each conduit extending to the water surface, adds considerable cost and assemblage time to the fabrication of the jacket.
Another known grouting technique involves a primary grout supply conduit which extends from the water surface to a submerged manifold fixed to the jacket adjacent the pile sleeves. Secondary grout supply conduits extend from separate ports on the manifold to respective pile sleeves. Grout is conducted through the primary conduit and into one of the secondary conduits to which it is connected (via the manifold). Thereafter, a diver manually reconnects the primary supply conduit to another position on the manifold to communicate with another of the secondary supply conduits. In this manner, grout is sequentially delivered to the respective pile sleeves. The pile sleeves can be connected to secondary grout discharge lines which are also connected to the manifold for sequential hook-up with a primary discharge conduit by means of diver manipulation. Alternately, the pile sleeves can be left open at their upper ends, whereby the diver can view the progress of the grouting operation. Such a system exhibits certain shortcomings, especially as regards the need for manipulation by a diver.
Exemplary of various grouting techniques are those described in U.S. Pat. Nos. 3,209,544 issued to Borrmann on Oct. 5, 1965, 3,213,629 issued to Manning on Oct. 26, 1965, 3,492,824 issued to Evans et al on Feb. 3, 1970, 3,878,687 issued to Tragesser, Jr. on Apr. 22, 1975 and 4,009,581 issued to Britton et al on Mar. 1, 1977. The techniques disclosed in those patents are so dissimilar to the present invention that they demonstrate the unobviousness of the latter.
It is, therefore, an object of the present invention to minimize or obviate drawbacks of the type previously noted.
It is another object of the invention to provide novel apparatus for grouting submerged pile sleeves.
It is a further object of the invention to enable submerged pile sleeves to be grouted without the assistance of a diver.
It is an additional object of the invention to provide novel apparatus for grouting submerged pile sleeves which minimizes the needed amount of grouting conduit.
It is still a further object of the invention to provide novel apparatus for grouting submerged pile sleeves in which a mechanized subsea carriage travels in step-by-step fashion along the inlets of a row of secondary grout conduits. A movable arm on the carriage is attached to a primary grout conduit and is actuated to communicate the primary grout supply conduit with a secondary grout conduit.